Extra fields on specific Help Topic?

Hi everyone,

I need to add extra fields that only shows when I'm choosing a specific Help Topic.

Example:

If I choose "Damage in transit" these extra fields will pop up:

Packaging damage: ________

Product damage: _________

These fields won't show up if I choose any other Help Topic, e.g. Warehouse Issue.

Anyone who has an idea on how to do this? I've searched for it for a while but haven't seen any other similar questions/mods.

Thanks alot!